1. Field of the Invention
The present invention relates to a scroll type hydraulic machine suitable as a compressor for a refrigerating circuit constituting an air conditioning system.
2. Description of the Related Art
This type of hydraulic machine, that is, a scroll type compressor is provided to a refrigerating circuit, and is disposed in an automobile, for example, inside an engine room. More specifically, a compressor is connected to an evaporator, a condenser as well as an expansion valve. These condenser and expansion valve are disposed inside the engine room while the evaporator is disposed in a vehicle interior.
This compressor comprises a scroll unit, that is, a stationary scroll as well as a movable scroll, inside a compression casing, suctions refrigerant from the evaporator side and compresses by causing the movable scroll to rotate with respect to the stationary scroll and discharge this compressed refrigerant toward the condenser side.
In order to implement swivel actions of this movable scroll, it is necessary to intercept the shaft center of the stationary scroll, that is, rotation of the movable scroll around the rotation center without preventing orbital rotation of the movable scroll around the orbital center. Therefore, as a rotation interception mechanism for intercepting this rotation, such a compressor is known that comprises a plurality of binding members for binding its rotation between a drive casing and a substrate of the movable scroll, and brings these binding members into pin connection to both of the drive casing and the movable scroll (reference should be made to, for example, Japanese Laid-Open patent (Kokai) Publication No. 2001-90678).
According to this compressor, the swivel side pin and the fixed side pin are disposed in such a position that is determined from the orbital center and the rotation center so as to alleviate the load onto the pins, in such a position in which the volume of the compressing chamber reaches 20% to 28% of the volume at the time of completion of suction of fluid.
It should be added that, there exist three reference points in the movable scroll, that is, the above-mentioned orbital center as well as rotation center and, in addition, a gravity center. Further, in general, this rotation center is employed as the center of the substrate of the movable scroll. That is because the production of the scroll unit becomes easy.
Here, there is no problem in the case where the gravity center of the movable scroll and the rotation center match. On the other hand, the gravity center and the rotation center are disposed at slight distance and therefore do not match. That is because it is necessary to make the size in the scroll unit's radius direction smaller at the time of engagement between the stationary scroll and the movable scroll.
Further, the displacement quantity being distance between the gravity center and the rotation center generates torque around the rotation center by being multiplied by the centrifugal force arising in the movable scroll. That is, a load other than the original rotation intercepting force will arise in the pin of the rotation interception mechanism. In particular, since the above-mentioned centrifugal force is proportionate to the square of the rotation speed,-an excess load arises at the time of high speed, and the decrease in durability of the rotation interception mechanism is concerned.
However, the above-mentioned prior art determines disposition of the pin from the relationship between the orbital center and the rotation center with the gravity center of the movable scroll and the rotation center match as a precondition. In other words, on a problem in the case where the above-mentioned gravity center and rotation center do not match, no particular consideration is paid and the problems on the point of load decrease in pins still remain.